化简:当n=1/2时,求(3n-1)(n+1)+(2n-1)(n-1)的值.

问题描述:

化简:当n=1/2时,求(3n-1)(n+1)+(2n-1)(n-1)的值.

3n-1)(n+1)+(2n-1)(n-1)
=3n^2+3n-n-1+2n^2-2n-n+1
=5n^2-n
=5x(1/2)^2-1/2
=3/4